The present invention relates to an ink jet system printer which prints a desired pattern in a dot matrix fashion and, more particularly, to an ink jet system printer of the charge amplitude controlling type.
Generally, in an ink jet system printer of the charge amplitude controlling type, ink droplets of a uniform size are emitted from an ink droplet issuance unit at a given frequency and charged to desired amplitudes in accordance with print data. The thus charged ink droplets are deflected in accordance with the charge amplitude carried thereon as they pass through a constant high voltage field established by a deflection means and deposited at desired positions on a record receiving paper, thereby printing desired patterns in a dot matrix fashion.
More specifically, the deflection in the column direction is controlled by selecting the charge amplitude in an analog fashion, whereas the positioning in the row direction is achieved by driving a carriage to travel in the row direction at a constant speed. Therefore, the print velocity is limited to a specific value, and when the dot number for one matrix pattern is increased, the print velocity is considerably reduced because only one ink droplet issuance unit is employed in the system.
Moreover, when the matrix pattern comprises 5.times.7 ink droplets, the charge signal must be graded in eight levels. Therefore, the control circuit is complicated, and there is a possibility that print distortion occurs due to the charge error. Moreover, it is unavoidable that the print pattern is ultimately inclined because the carriage is driven to travel in the row direction at a constant speed even during the one column printing.
A typical ink jet system for conducting one column printing was disclosed in U.S. Pat. No. 3,373,437, entitled "FLUID DROPLET RECORDER WITH A PLURALITY OF JETS" on Mar. 12, 1968, wherein a plurality of orifices are provided in a manifold for emitting a plurality of jets. However, it is impossible to accurately control the phase of formation of the ink droplets in the respective jets in U.S. Pat. No. 3,373,437.